Torque generators have been in commercial use for many years. A typical torque generator is capable of translating a relatively low-torque input into a relatively high-torque steering output with the aid of a source of pressurized fluid. Example torque generators are disclosed by U.S. Pat. No. RE 25,291 and U.S. Pat. No. 4,936,094.
Known torque generators can include a valve arrangement including a spool that extends through a sleeve. The spool and the sleeve are coaxially aligned along an axis, and a limited range of relative rotational movement about the axis is permitted between the spool and the sleeve. The valve arrangement is normally biased toward a neutral state (i.e., position, configuration, etc.). The valve arrangement is displaced from the neutral state to an operating state by rotation of a steering wheel coupled to the spool. When the valve arrangement is in the operating state, pressurized fluid flows through the valve arrangement and into a fluid pressure actuated displacement mechanism, such as a gerotor gear set, thereby generating a relatively high-torque steering output which is transmitted through an output shaft to a steering apparatus, such as the pinion gear of a rack and pinion device. While torque generators are particularly advantageous when used in vehicle steering systems, and will be described in connection therewith, it will be appreciated that torque generators can also be used in various other applications.